The Difference Between Concrete and Cement
Concrete is one of the most common building materials used in modern construction. Middle Eastern builders used a crude precursor to concrete as early as 6500 B.C. They found that if they coated the outside of their walls with burned limestone, it resulted in a protective surface much harder than the pounded clay walls themselves. The terms “concrete” and “cement” get used interchangeably, but they are not the same.
Cement is an ingredient of concrete. The most common type of modern concrete is what’s known as portland cement. Portland cement gets its name from its inventor, Joseph Aspdin. He created it by burning chalk and clay until all of the carbon dioxides in the minerals were gone. Aspdin named his invention after a quarry in Portland, England known for its building stones. Portland cement is a hydraulic cement; water gets added to the mixture, which initiates the chemical reactions needed for the adhesive to harden and set.
Concrete is a mix of aggregates and paste. Usually, contractors use portland cement and water as the paste, and the aggregates are typically sand, gravel, or crushed stone. Concrete gets stronger, the longer it sets because the hardening process involves the formation of tiny crystals over time. Different mixes of concrete exist depending on the climate of the area in which the concrete will set; freezing and thawing conditions require the addition of an air-entraining admixture. This admixture contains millions of bubbles that protect the concrete from the damaging effects of repetitive freezing and thawing in some climates.
History of Concrete
The earliest known use of concrete occurred in the Middle East around 6500 B.C. Traders in regions now known as Syria and Jordan created concrete floors, homes, and underground water storage.
Egyptians used 500,000 tons of mortar to build the Great Pyramids at Giza. They also mixed mud with straw to “cement” together bricks. Additionally, a type of cement was used to make the Great Wall of China along the historical northern borders of China around this time.
The ancient Romans were not the first to use versions of concrete or cement, but many of their structures are still standing after more than 2,000 years. The mixture of volcanic ash, lime, and seawater gets regarded as the most durable building material in history. After making the mixture, ancient Roman builders would pour it into molds made from wooden forms; once the concrete set, these blocks get stacked on each other like bricks.
The Sebastos Harbor in Caesarea, Israel was built. Construction took eight years, but the result was one of the biggest harbors in the world. The port is still intact, more than 2,000 years later, but it is underwater since it was built directly on a fault line in the Mediterranean.
The Roman Empire fell after 1000 years of order in western Europe when the Barbarian Odoacer overthrew Romulus, the last Roman emperor in the west. As a result, the recipe and technique for making polazzo cement got lost for nearly a thousand years.
Manuscripts get discovered in which the process for making polazzo cement gets described. This rekindled interest in building structures with concrete.
John Smeaton of England discovered a better way to produce hydraulic lime. He fired limestone that contained clay until it turned into clinker, which is little lumps of limestone and clay. Then, pieces get ground into a powder used in the production of cement. Smeaton used his new material when the Eddystone Lighthouse in Cornwall, England got rebuilt.
Joseph Aspdin invented Portland cement. This period gets credited as the beginning of “modern” cement and concrete.
Joseph Monier, a French gardener from Saint-Quentin-la-Poterie, invented reinforced concrete. Monier discovered that if concrete slabs get reinforced with steel rods where the most tensile stress occurs, this dramatically increases the concrete’s strength and durability.
The first reinforced-concrete home built in England. The builder William B. Wilkinson reinforced the roof and floors of a two-story cottage with iron bars and wire rope.
The first reinforced concrete bridge built in San Francisco, California. Alvord Lake Bridge still stands today, over a century after its construction.
The first concrete street constructed in Bellefontaine, Ohio.
The first commercial concrete high-rise built in Cincinnati, Ohio. The Ingalls Building is sixteen stories tall and still stands today.
Thomas Edison designed the first concrete homes in the United States. The houses, built in Union, New Jersey, still exist today, though the design did not gain as much popularity as Edison had hoped. Concrete homes are only just now, more than 100 years later, gaining in popularity.
The first batch of ready-mix gets delivered to a construction site in Baltimore, Maryland. The ability to provide concrete from a central plant to a construction site revolutionized the industry.
The first air-entraining agents were introduced to protect concrete from freezing and thawing.
The Hoover Dam, on the border of Arizona and Nevada, was completed. At the time, it was the most massive concrete structure ever built.
Brad Bowman developed decorative concrete in Monterey, California.
Fiber reinforcement developed as a way to strengthen concrete.
The tallest reinforced concrete building completed in Chicago, Illinois. The building is 65 stories tall and located at 311 South Wacker Drive.
Polished concrete was introduced to the United States by HTC, a Swedish company. The first polished concrete floor installed in the United States was at the Bellagio in Las Vegas, Nevada. The 40,000 square-foot warehouse floor was just the beginning of the refined concrete trend; today, many retail and educational buildings use polished concrete for flooring.
Looking Forward To Concrete
Developments and innovations in the world of concrete are constant; there is a huge demand for improved concrete, particularly in regions prone to flooding and storm surges. Scientists know that polazzo cement’s essential ingredient was volcanic ash. However, they still have not been able to replicate the strength found in ancient Roman concrete. The hope is to combine the ancient Romans’ secret concrete recipe with modern reinforcement technology to create concrete even stronger than that found in the Colosseum.